1. Field of the Invention
The present invention relates, in general, to data processing system power source selection devices.
2. Description of the Related Art
Data processing systems are systems that manipulate, process, and store data and are notorious within the art. Personal computer systems, and their associated subsystems, constitute well known species of data processing systems.
One particularly popular type of personal computer system is the portable computer system (e.g., laptop, notebook, sub-notebook, and palm-held computer systems). Portable computer systems allow stand-alone computing and typically have their own power-supplies, modems, and storage devices.
In order to allow maximum flexibility of use, portable computer systems typically utilize a xe2x80x9cmixxe2x80x9d of different types of power supplies. For example, a portable computer system typically has at least one external power supply adapter (e.g., an AC-DC adapter, or a cigarette lighter adapter), which will allow the portable computer to be powered from an external power outlet such as an AC wall outlet, or a cigarette lighter outlet in an automobile. In addition, a portable computer system typically has at least one rechargeable battery, which serves as an internal power supply and which allows the portable computer system to be powered up and used in remote locations where no external power supplies are present.
Because it is common for user requirements to exceed battery life, most portable computer systems provide slots and circuitry to support multiple (i.e., more than one) rechargeable batteries. Thus, in a typical portable computer system, it is very likely that the portable computer system will provide slots and circuitry for at least two batteries, as well as circuitry to support at one least external power supply, such as an AC-DC adapter power supply. Because of the presence of these multiple power supplies, it is necessary to provide circuitry to select which of the multiple power supplies will be utilized to power the portable computer system. One type of power supply selection circuitry which is used in the art relies on what is known as a xe2x80x9cbreak before makexe2x80x9d architecture.
With reference now to FIG. 1, shown is a partially schematic diagram of a xe2x80x9cbreak before makexe2x80x9d architecture 101. Depicted are three power sources: AC-DC adapter power supply 100, battery A 102, and battery B 104. AC-DC adapter power supply 100 supplies power to data processing system 200 through system power rail 106 when AC-DC power switch 108 is closed. Battery A 102 supplies power to data processing system 200 through system power rail 106 when Battery A power switch 110 is closed. Battery B 104 supplies power to data processing system 200 through system power rail 106 when Battery B power switch 112 is closed.
It is accepted in the art that cross conduction between the multiple power sources AC-DC adapter power supply 100, Battery A 102, and Battery B 104, is undesirable. Accordingly, break before make architecture 101 xe2x80x9cbreaksxe2x80x9d any existing electrical connection between a first power source and system power rail 106 before it xe2x80x9cmakesxe2x80x9d another electrical connection between a second power source and system power rail 106, which ensures that no cross conduction between various power sources takes place.
In practice, this is achieved by control circuit 114 which controls and coordinates AC-DC power switch 108, Battery A power switch 110, and Battery B power switch 112 such that neither AC-DC adapter power supply 100, nor Battery A 102, nor Battery B 104 are ever simultaneously connected with each other (i.e., simultaneously connected with system power rail 106). When an existing connection between a first power supply and system rail 106 is xe2x80x9cbroken,xe2x80x9d and before a new connection between a second power supply and system rail 106 is established, there exists a period of time during which no power supply is connected to system power rail 106. Those skilled in the art will recognize that it is imperative that the voltage on system power rail 106 be xe2x80x9cheld upxe2x80x9d during this instant of time. This function is provided by very large bulk capacitance 116, which serves to maintain the voltage on system power rail 106 during the period of time in which no power supply is connected to system power rail 106. Accordingly, very large bulk capacitance 116 is shown connected in parallel with data processing system 200.
The systemic functionalities and protections provided by break before make architecture 101 are desirable and necessary. However, those skilled in the art will recognize that there is tremendous space-efficiency and cost-efficiency pressure in the portable computer market. Those skilled in the art will also recognize that there is tremendous pressure in the art for constantly improved computing systems which maintain compatibility with previous generation systems.
Accordingly, it is apparent that there is a need in the art for a device, compatible with existing and previous generation systems, which provides the systemic functionalities and protections of break before make architectures and which gives a space-efficiency and cost-efficiency advantage over break before make architectures.
A system power supply selection device has been discovered, compatible with existing and previous generation systems, which provides the systemic functionalities and protections of break before make architectures, and gives a space-efficiency and cost-efficiency advantage over break before make architectures. The system power supply selection device can include a first make-without-break power supply selector module having a power supply input, at least one controlling power supply input, and a system power rail output substantially continuously coupled to said at least a first power supply input.
The foregoing is a summary and thus contains, by necessity, simplifications, generalizations and omissions of detail; consequently, those skilled in the art will appreciate that the summary is illustrative only and is not intended to be in any way limiting. Other aspects, inventive features, and advantages of the present invention, as defined solely by the claims, will become apparent in the non-limiting detailed description set forth below.